Synthesis and reactions of 2‐amino‐6‐(3‐methyl‐5‐oxo‐1‐phenyl‐2‐pyrazolin‐4‐yl)‐4‐phenylpyridine‐3‐carbonitrile

2‐Amino‐6‐(3‐methyl‐5‐oxo‐1‐phenyl‐2‐pyrazolin‐4‐yl)‐4‐phenylpyridine‐3‐carbonitrile (1) obtained by the reaction of 4‐(1‐iminoethyl)‐3‐methyl‐1‐phenyl‐2‐pyrazolin‐5‐one with benzylidenemalononitrile, was reacted with triethyl orthoformate followed by hydrazine hydrate, acetic anhydride, acetyl chloride, alkyl halides, benzoyl chloride, sulphuric acid followed by formamide, phenyl isothiocyanate, carbon disulphide followed by ethyl iodide, formamide, trichloroacetonitrile, nitrous acid, giving new oxopyrazolinylpyridines ( 2,3,5,6,8,9,10 ) and related pyridopyrimidines ( 11‐17 ) and pyridotriazine ( 18 ).     

Nucleophilic addition to 3‐methyl‐1‐(4‐nitrophenyl)‐2‐phenyl‐4,5‐dihydroimidazolium iodide

Reactions of the 1,2‐diaryl 4,5‐dihydroimidazolium, represented by 3‐methyl‐1‐(4‐nitrophenyl)‐2‐phenyl‐4,5‐dihydroimidazolium iodide 1 , with ethylenediamine afforded a benzylidyne unit transferred product, 2‐phenyl‐2‐imidazoline 2 ; a ring‐opened adduct 4 was produced when excess ethylenediamine was used. Reactions of 1 with hydroxylamine, malononitrile, and nitromethane anions produced ring‐opened products, 5 , 7 , and 8 respectively.     

Synthesis and Solid‐state Reaction of 1‐[3′‐(Benzotriazol‐2″‐yl)‐4′ ‐hydroxybenzoyl]‐3‐methyl‐5‐pyrazolones

A new kind of UV stabilizers, 1‐(3′‐(benzotriazol‐2″‐yl)‐4′‐hydroxy‐benzoyl)‐3‐methyl‐5‐pyrazolones (1a‐d), was synthesized with the aim to bind them chemically to certain polymers. The reaction of 1d with substituted benzaldehydes 4 in the molten state at 150°C and in the solid state at room temperature produced the condensation products l‐(3′‐(5″‐chlorobenzotriazol‐2″‐yl)‐4′‐hydroxyl‐5′‐chlorobenzoyl)‐3‐methyl‐4‐arylmethylene‐5‐pyrazolones (2) and 4,4′‐arylmethylene‐bis [1‐(3′‐(5″‐chloro‐benzotriazol‐2″‐yl)‐4′‐hydroxy‐5′‐chloro‐benzoyl)‐3‐methyl‐5‐pyrazolone] s (3), respectively, as the major product. On the other hand, the reaction of 1d with 4 at 50°C in chloroform solution proceeded non‐selectively to give a mixture of 2 and 3.     

Hantzsch reaction of 3‐(2‐bromoacetyl)‐4‐hydroxy‐chromen‐2‐one. Synthesis of 3‐(thiazol‐4‐yl)‐4‐hydroxy coumarines

3‐Acetyl‐4‐hydroxy‐chromen‐2‐one ( 1 ) was brominated with phenyltrimethylammonium tribromide to afford 3‐(2‐bromoacetyl)‐4‐hydroxy‐chromen‐2‐one ( 2 ) whose reactions with thiourea, thioacetamide and ammonium dithiocarbamate gave respectively 3‐(2‐amino‐thiazol‐4‐yl)‐4‐hydroxy‐, 4‐hydroxy‐3‐(2‐phenyl‐thiazol‐4‐yl)‐ and 4‐hydroxy‐3‐(2‐mercapto‐thiazol‐4‐yl)chromen‐2‐one. In a similar manner, com pound 2 was treated with four 1‐substituted‐2‐thioureas and thiobenzamide to give the corresponding 4‐hydroxy‐3‐(thiazol‐4‐yl)‐chromen‐2‐one derivatives.     

Preparation of 2‐phenyl‐2‐hydroxymethyl‐4‐oxo‐1,2,3,4‐tetrahydroquinazoline and 2‐methyl‐4‐oxo‐3,4‐dihydroquinazoline derivatives formation

The cyclization of phenacyl anthranilate has been studied with the aim to develop the synthesis of 2‐(2′‐aminophenyl)‐4‐phenyloxazole. However, a different course of the reaction than expected was observed. 2‐Phenyl‐2‐hydroxymethyl‐4‐oxo‐1,2,3,4‐tetrahydroquinazoline ( 3a ) was formed by the reaction of phenacyl anthranilate ( 2 ) with ammonium acetate under various conditions. 3‐Hydroxy‐2‐phenyl‐4(1H)‐quinolinone ( 4 ) arose by heating compound 3a in acetic acid. The same compound was obtained by melting compound 3a , but the yield was lower. Different types of products resulted in the reaction of compound 3a with acetic anhydride. Under mild conditions acetylated products 2‐acetoxymethyl‐2‐phenyl‐4‐oxo‐1,2,3,4‐tetrahydroquinazoline ( 7a ) and 2‐acetoxymethyl‐3‐acetyl‐2‐phenyl‐4‐oxo‐1,2,3,4‐tetrahydroquinazoline ( 8 ) were prepared. If the reaction was carried out under reflux of the reaction mixture, molecular rearrangement took place to give cis and trans 2‐methyl‐4‐oxo‐3‐(1‐phenyl‐2‐acetoxy)vinyl‐3,4‐dihydroquinazolines ( 9a and 9b ). All prepared compounds have been characterised by their ¹H, ¹³C and ¹⁵N NMR spectra, IR spectra and MS.     

New domino‐reaction for the synthesis of N4‐(5‐aryl‐1,3‐oxathiol‐2‐yliden)‐2‐phenylquinazolin‐4‐amines and 4‐[4‐aryl‐5‐(2‐phenylquinazolin‐4‐yl)‐1,3‐thiazol‐2‐yl]morpholine

The model morpholine‐1‐carbothioic acid (2‐phenyl‐3H‐quinazolin‐4‐ylidene) amide (1) reacts with phenacyl bromides to afford N⁴‐(5‐aryl‐1,3‐oxathiol‐2‐yliden)‐2‐phenylquinazolin‐4‐amines (4) or N⁴‐(4,5‐diphenyl‐1,3‐oxathiol‐2‐yliden)‐2‐phenyl‐4‐aminoquinazoline ( 5 ) by a thermodynamically controlled reversible reaction favoring the enolate intermediate, while the 4‐[4‐aryl‐5‐(2‐phenylquinazolin‐4‐yl)‐1,3‐thiazol‐2‐yl]morpholine ( 8 ) was produced by a kinetically controlled reaction favoring the C‐anion intermediate. ¹H nmr, ¹³C nmr, ir, mass spectroscopy and x‐ray identified compounds ( 4 ), ( 5 ) and ( 8 ).     

Preparation and Reactions of 2‐Methyl‐7‐(3‐methyl‐5‐oxo‐1‐phenyl‐2‐pyrazolin‐4‐yl)‐5‐arylthiazolo[3,2‐a]‐pyrimido[4,5‐d]oxazin‐4(5H)‐one

Ethyl 7‐amino‐3‐(3‐methyl‐5‐oxo‐1‐phenyl‐2‐pyrazolin‐4‐yl)‐5‐aryl‐5H‐thiazolo[3,2‐a]pyrimidine‐6‐carboxylate was hydrolyzed with an ethanolic sodium hydroxide and the sodium salt thus formed underwent cyclization with acetic anhydride to afford 2‐methyl‐7‐(3‐methyl‐5‐oxo‐1‐phenyl‐2‐pyrazolin‐4‐yl)‐5‐arylthiazolo[3,2‐a]pyrimido[4,5‐d]oxazin‐4(5H)‐one. This compound was transformed to related heterocyclic systems via its reaction with various reagents. The biological activity of the prepared compounds was tested against Gram positive and Gram negative bacteria as well as yeast‐like and filamentous fungi. They revealed in some cases excellent biocidal properties.     

Synthesis and Heterocyclization of 1‐Aryl‐2‐methyl‐4‐oxo‐1,4,5,6‐tetrahydropyridine‐3‐carboxylates

A series of novel isoxazole, dihydropyrazolone, and tetrahydropyridine derivatives were synthesized by the reaction of corresponding ethyl 1‐substituted aryl‐2‐methyl‐4‐oxo‐1,4,5,6‐tetrahydropyridine‐3‐carboxylates with different hydrazines and hydroxylamine. Reaction of tetrahydropyridone with N ,N‐dimethylformamide dimethyl acetal provided 1‐(5‐chloro‐2‐methylphenyl)‐2‐[2‐(dimethylamino)ethenyl]‐4‐oxo‐1,4,5,6‐tetrahydropyridine‐3‐carboxylate, which was cyclized into a bicyclic compound on treatment with ammonium acetate. The structures of all synthesized compounds were confirmed by IR, ¹H NMR, and ¹³C NMR spectroscopy data. The structure of 5‐(5‐chloro‐2‐methylphenyl)‐4‐methyl‐2‐phenyl‐2,5,6,7‐tetrahydro‐3H‐pyrazolo[4,3‐c]pyridin‐3‐one was unambiguously assigned by means of X‐ray analysis data.     

7‐Halogenated 7‐Deaza‐2′‐deoxyxanthine 2′‐Deoxyribonucleosides

The synthesis of the 7‐halogenated derivatives 1b (7‐bromo) and 1c (7‐iodo) of 7‐deaza‐2′‐deoxyxanthosine ( 1a ) is described. A partial Br→I exchange was observed when the demethylation of 6‐methoxy precursor compound 4b was performed with Me₃SiCl/NaI. This reaction is circumvented by the nucleophilic displacement of the MeO group under strong alkaline conditions. The halogenated 7‐deaza‐2′‐deoxyxanthosine derivatives 1b , c show a decreased S‐conformer population of the sugar moiety compared to the nonhalogenated 1a . They are expected to form stronger triplexes when they replace 1a in the 1 ?dA?dT base triplet.     

Synthesis of 15‐Cyano‐12‐oxopentadecano‐15‐lactone and 15‐Cyano‐ 12‐oxopentadecano‐15‐lactam

15‐Cyano‐12‐oxopentadecano‐15‐lactone was synthesized in 59% total yield starting from 2‐nitrocyclododecanone by Michael addition to acrylaldehyde, followed by reaction with trimethylsilylcyanide, hydrolysis, ring‐expansion, and Nef reaction. A two‐step, one‐pot synthesis of intermediate 2‐hydroxy‐4‐(1‐nitro‐2‐oxycyclododecyl)butanenitrile from 3‐(1‐nitro‐2‐oxocyclododecyl)propanal was developed and the conditions for the Nef reaction were studied. 15‐Cyano‐12‐oxopentadecano‐15‐lactam was synthesized in 40% total yield starting from 2‐nitrocyclododecanone by Michael addition to acrylaldehyde, followed by Strecker reaction, ring‐expansion, and Nef reaction. The conditions for the Strecker and Nef reactions were studied. The structures of the target compounds, intermediates, and by‐product were characterized by IR, ¹H‐ and ¹³C‐NMR, and elemental analysis or MS.     

2‐(Pyrrolidin‐1‐yl)‐1,4‐naphtho­quinone and 2‐phenyl­sulfanyl‐3‐(pyrrolidin‐1‐yl)‐1,4‐naphtho­quinone

The structure of 2‐(pyrrolidin‐1‐yl)‐1,4‐naphtho­quinone, C₁₄H_12.95Cl_0.05NO₂, (I), is actually a 0.95:0.05 mixture including 2‐chloro‐3‐(pyrrolidin‐1‐yl)‐1,4‐naphtho­quinone as a minor impurity, but (I) was resolved as a single molecule containing a Cl atom with 5% occupancy at the 3‐position. Compound (I) was prepared from the fully chloro‐substituted analogue in an attempt to produce the disubstituted pyrrolidinyl derivative. 2‐Phenyl­sulfanyl‐3‐(pyrrolidin‐1‐yl)‐1,4‐naphtho­quinone, C₂₀H₁₇NO₂S, (II), was also prepared from 2‐chloro‐3‐(pyrrolidin‐1‐yl)‐1,4‐naphtho­quinone, using a strong exocyclic nucleophile. The structure of (II) differs from previous structures of 2,3‐di­chloro‐1,4‐naphtho­quinone and its derivatives in that the naphtho­quinone ring is non‐planar.     

A simple synthesis of 5‐ethoxycarbonyl‐6‐phenyl‐1,3‐dioxin‐4‐ones and ethyl 3‐benzoyl‐4‐oxo‐2,6‐diphenylpyran‐5‐carboxylate

4‐Ethoxycarbonyl‐5‐phenyl‐2,3‐dihydrofuran‐2,3‐dione 1 reacts with aldehydes via the acylketene intermediate 2 giving the 1,3‐dioxin‐4‐ones 3a‐e and the 1,4‐bis(5‐ethoxycarbonyl‐4‐oxo‐6‐phenyl‐4H‐1,3‐dioxin‐2‐yl)benzene 4 , and a one step reaction between dibenzoylmethane and oxalylchloride gave 3,5‐dibenzoyl‐2,6‐diphenyl‐4‐pyrone 7 . The reaction of 1 with dibenzoylmethane, a dicarbonyl compound, provided ethyl 3‐benzoyl‐4‐oxo‐2,6‐diphenylpyran‐5‐carboxylate derivative 9 . Compound 9 was converted into the corresponding ethyl 3‐benzoyl‐4‐hydroxy‐2,6‐diphenylpyridine‐5‐carboxylate derivative 10 via its reaction with ammonium hydroxyde solution in 1 ‐butanol.     

立体选择性合成2-(a-噻吩甲酰基)-3-取代苯基-4-乙氧羰基-5-甲基-反式-2,3-二氢呋喃

溴化(a-噻吩甲酰基)甲基三苯鉮1与3-取代苯甲叉基-2,4-戊二酮 2以碳酸钾为碱,在苯中55℃条件下反应,可以较好的收率、高立体选择性地生成反-2-(a-噻吩甲酰基)-3-取代苯基-4-乙氧羰基-5-甲基-2,3-二氢呋喃3。产物结构均经波谱予以确定。本文还提出了生成产物的可能机理。     

Acid Catalyzed tert‐Butylation and Tritylation of 4‐Nitro‐1,2,3‐triazole: Selective Synthesis of 1‐Methyl‐5‐nitro‐1,2,3‐triazole via 1‐tert‐Butyl‐4‐nitro‐1,2,3‐triazole

4‐Nitro‐1,2,3‐triazole was found to react with tert‐butanol in concentrated sulfuric acid to yield 1‐tert‐butyl‐4‐nitro‐1,2,3‐triazole as the only reaction product, whereas tert‐butylation and tritylation of 4‐nitro‐1,2,3‐triazole in presence of catalytic amount of sulfuric acid in benzene was found to provide mixtures of isomeric 1‐ and 2‐alkyl‐4‐nitro‐1,2,3‐triazoles with predominance of N2‐alkylated products. A new methodology for preparation of 1‐alkyl‐5‐nitro‐1,2,3‐triazoles from 1‐tert‐butyl‐4‐nitro‐1,2,3‐triazole via exhaustive alkylation followed by removal of tert‐butyl group from intermediate triazolium salts was demonstrated by the example of preparation of 1‐methyl‐5‐nitro‐1,2,3‐triazole.     

Polymorphism of 3‐(5‐phenyl‐1,3,4‐oxadiazol‐2‐yl)‐ and 3‐[5‐(pyridin‐4‐yl)‐1,3,4‐oxadiazol‐2‐yl]‐2H‐chromen‐2‐ones

This study of 3‐(5‐phenyl‐1,3,4‐oxadiazol‐2‐yl)‐2H‐chromen‐2‐one, C₁₇H₁₀N₂O₃, 1 , and 3‐[5‐(pyridin‐4‐yl)‐1,3,4‐oxadiazol‐2‐yl]‐2H‐chromen‐2‐one, C₁₆H₉N₃O₃, 2 , was performed on the assumption of the potential anticancer activity of the compounds. Three polymorphic structures for 1 and two polymorphic structures for 2 have been studied thoroughly. The strongest intermolecular interaction is stacking of the `head‐to‐head' type in all the studied crystals. The polymorphic structures of 1 differ with respect to the intermolecular interactions between stacked columns. Two of the polymorphs have a columnar or double columnar type of crystal organization, while the third polymorphic structure can be classified as columnar‐layered. The difference between the two structures of 2 is less pronounced. Both crystals can be considered as having very similar arrangements of neighbouring columns. The formation of polymorphic modifications is caused by a subtle balance of very weak intermolecular interactions and packing differences can be identified only using an analysis based on a study of the pairwise interaction energies.     

Synthese und Reaktivität von 2‐Brom‐1,3‐diethyl‐2,3‐dihydro‐1 H‐1,3,2‐benzodiazaborol Molekülstruktur von Bis(1,3‐diethyl‐2,3‐dihydro‐1 H‐1,3,2‐benzodiazaborol‐2‐yl)

Synthesis and Reactivity of 2‐Bromo‐1,3‐diethyl‐2,3‐dihydro‐1 H ‐1,3,2‐benzodiazaborole Molecular Structure of Bis(1,3‐diethyl‐2,3‐dihydro‐1 H ‐1,3,2‐benzodiazaborol‐2‐yl The reaction of a slurry of calcium hydride in toluene with N,N′‐diethyl‐o‐phenylenediamine ( 1 ) and boron tribromide affords 2‐bromo‐1,3‐diethyl‐2,3‐dihydro‐1 H‐1,3,2‐benzodiazaborol ( 2 ) as a colorless oil. Compound 2 is converted into 2‐cyano‐1,3‐diethyl‐2,3‐dihydro‐1 H‐1,3,2‐benzodiazaborole ( 3 ) by treatment with silver cyanide in acetonitrile. Reaction of 2 with an equimolar amount of methyllithium affords 1,3‐diethyl‐2‐methyl‐2,3‐dihydro‐1 H‐1,3,2‐benzodiazaborole ( 4 ). 1,3,2‐Benzodiazaborole is smoothly reduced by a potassium‐sodium alloy to yield bis(1,3‐diethyl‐2,3‐dihydro‐1 H‐1,3,2‐benzodiazaborol‐2‐yl] ( 7 ), which crystallizes from n‐pentane as colorless needles. Compound 7 is also obtained from the reaction of 2 and LiSnMe₃ instead of the expected 2‐trimethylstannyl‐1,3,2‐benzodiazaborole. N,N′‐Bis(1,3‐diethyl‐2,3‐dihydro‐1 H‐1,3,2‐benzodiazaborol‐2‐ yl)‐1,2‐diamino‐ethane ( 6 ) results from the reaction of 2 with Li(en)C≡CH as the only boron containing product. Compounds 2 – 4 , 6 and 7 are characterized by means of elemental analyses and spectroscopy (IR, ¹H‐, ¹¹B{¹H}‐, ¹³C{¹H}‐NMR, MS). The molecular structure of 7 was elucidated by X‐ray diffraction analysis.     

Synthesis of new substituted 5‐methyl‐3,5‐diphenylimidazolidine‐2,4‐diones from substituted 1‐(1‐cyanoethyl‐1‐phenyl)‐3‐phenylureas

The reaction of substituted phenyl isocyanates with 2‐amino‐2‐phenylpropanenitrile and 2‐amino‐2‐(4‐nitrophenyl)propanenitrile has been used to prepare substituted 1‐(1‐cyanoethyl‐1‐phenyl)‐3‐phenylureas. In anhydrous phosphoric acid the first products to be formed from 1‐(1‐cyanoethyl‐1‐phenyl)‐3‐phenylureas are phosphates of 4‐methyl‐4‐phenyl‐2‐phenylimino‐5‐imino‐4,5‐dihydro‐1,3‐oxazoles, which on subsequent hydrolysis give the respective ureidocarboxylic acids. On prolongation of the reaction time, the phosphates of 4‐methyl‐4‐phenyl‐2‐phenylimino‐5‐imino‐4,5‐dihydro‐1,3‐oxazoles rearrange to give phosphates of 5‐methyl‐4‐imino‐3,5‐diphenylimidazolidin‐2‐ones, and these are subsequently hydrolysed to the respective substituted 5‐methyl‐3,5‐diphenylimidazolidin‐2,4‐diones. The ureidocarboxylic acids were also prepared by alkaline hydrolysis of 5‐methyl‐3,5‐diphenylimidazolidin‐2,4‐diones. The 5‐methyl‐3,5‐diphenylimidazolidin‐2,4‐diones and ureidocarboxylic acids were characterised by their ¹H and ¹³C NMR spectra. Structure of the 5‐methyl‐5‐(4‐nitrophenyl)‐3‐phenylimidazolidine‐2,4‐dione was verified by X‐ray diffraction. The alkaline hydrolysis of individual imidazolidine‐2,4‐diones was studies spectrophoto‐metrically in sodium hydroxide solutions at 25 °C. The rate‐limiting step of the base catalysed hydrolysis consists in decomposition of the tetrahedral intermediate. The reaction is faster if electron‐acceptor sub‐stituents are present in the 3‐phenyl group of imidazolidine‐2,4‐dione cycle. The pK_a values of individual 5‐methyl‐3,5‐diphenylimidazolidine‐2,4‐diones have been determined kinetically.     

Synthesis of optically active af‐(1‐Ethyl‐3‐methylhexahydro‐1,3‐diazin‐5‐yl)‐ and N‐(1‐Ethyl‐5‐methyloctahydro‐1,5‐diazocin‐3‐yl)pyridine‐3‐carboxamides

As part of the structure‐activity relationship of the dopamine D₂ and serotonin 5‐HT₃ receptors antagonist 1, which is a clinical candidate with a broad antiemetic activity, the synthesis and dopamine D₂ and serotonin 5‐HT₃ receptors binding affinity of (R)‐5‐bromo‐N‐(1‐ethyl‐3‐methylhexahydro‐1,3‐diazin‐5‐yl)‐ and (R)‐5‐bromo‐N‐(1‐ethyl‐5‐methyloctahydro‐1,5‐diazocin‐3‐yl)‐2‐methoxy‐6‐methylaminopyridine‐3‐carboxam‐ides ( 2 and 3 ) are described. Treatment of 1‐ethyl‐2‐(p‐toluenesulfonyl)amino‐3‐methylaminopropane dihy‐drochloride ( 4a ) with paraformaldehyde and successive deprotection gave the 5‐aminohexahydro‐1,3‐diazine 6 in excellent yield. 3‐Amino‐1‐ethyl‐5‐methyloctahydro‐1,5‐diazocine ( 15 ) was prepared from 2‐(benzyloxycarbonyl)amino‐3‐[[N‐(tert‐butoxycarbonyl)‐N‐methyl]amino]‐1‐ethylaminopropane ( 9 ) through the intramolecular amidation of (R)‐3‐[N‐[(2‐benzyloxycarbonylamino‐3‐methylamino)propyl]‐N‐ethyl]aminopropionic acid trifluoroacetate ( 12 ), followed by lithium aluminum hydride reduction of the resulting 6‐oxo‐1‐ethyl‐5‐methyloctahydrodiazocine ( 13 ) in 41% yield. Reaction of the amines 6 and 15 with 5‐bromo‐2‐methoxy‐6‐methylaminopyridine‐3‐carboxylic acid furnished the desired 2 and 3 , which showed much less potent affinity for dopamine D₂ receptors than 1 .     

Synthesis of novel 2‐(2‐methylsulfonyl‐1‐methyl‐1H‐imidazol‐5‐yl)‐5‐(alkylsulfonyl)‐1,3,4‐thiadiazoles

Starting from 5‐hydroxymethyl‐2‐mercapto‐1‐methyl‐1H‐imidazole (1), a series of 2‐(1‐methyl‐2‐methylsulfonyl‐1H‐imidazol‐5‐yl)‐5‐alkylthio and 5‐alkylsulfonyl‐1,3,4‐thiadiazole derivatives ( 9a , 9b , 9c , 9d and 10a , 10b , 10c , 10d ) were prepared as potential antimicrobial agents. The structure of the obtained compounds was confirmed by NMR, IR, Mass spectroscopy, and elemental analysis. J. Heterocyclic Chem., (2010)     

New routes to 1‐functionally substituted arylbenzotriazoles: 3‐Benzotriazol‐1‐yl‐pyridazine‐4‐ones, 5‐benzotriazol‐1‐yl‐pyridazine‐6‐ones and 5‐benzotriazol‐1‐yl‐pyridazine‐6‐imines

Condensation of 1‐arylhydrazono‐1‐benzotriazol‐1‐yl 2‐propanones ( 5a‐c ) with DMF DMA afforded 1‐aryl‐3‐benzotriazol‐1‐yl‐1,4‐dihydropyridazine‐4‐ones ( 8a‐c ). While condensation of 1‐functionally substituted methylbenzotriazoles 3b,c with 2‐arylhydrazono‐3‐oxoarylpropanal 13a,b give 3‐aroyl‐5‐(benzo‐triazolyl‐1‐yl)‐1,6‐dihydro‐1‐phenylpyridazine‐6‐ones and 6‐imines 14a‐d.